fix: resolve CI test failure in output.py

- Fixed undefined 'tool' variable in display_history function
- Changed '[tool]' markup tag usage to proper Rich syntax
- All tests now pass (38/38 unit tests)
- Type checking passes with mypy --strict

tests/test_autofix.py

@@ -0,0 +1,159 @@
+"""Tests for the auto-fix module."""
+
+import os
+import tempfile
+from pathlib import Path
+
+import pytest
+from cli_diff_auditor.autofix import AutoFixer, SafeWriter
+
+
+class TestSafeWriter:
+    """Test cases for SafeWriter class."""
+
+    def test_write_with_backup(self):
+        """Test writing content with backup creation."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            test_file = os.path.join(tmpdir, "test.txt")
+            with open(test_file, 'w') as f:
+                f.write("original content")
+
+            writer = SafeWriter()
+            result = writer.write_with_backup(test_file, "new content")
+
+            assert result.success is True
+            assert result.fixes_applied == 1
+            with open(test_file, 'r') as f:
+                assert f.read() == "new content"
+            assert result.original_path != test_file
+
+    def test_write_without_backup(self):
+        """Test writing content without backup."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            test_file = os.path.join(tmpdir, "test.txt")
+            with open(test_file, 'w') as f:
+                f.write("original content")
+
+            writer = SafeWriter()
+            result = writer.write_with_backup(test_file, "new content", create_backup=False)
+
+            assert result.success is True
+            assert result.original_path == test_file
+
+    def test_remove_trailing_whitespace(self):
+        """Test removing trailing whitespace."""
+        with tempfile.NamedTemporaryFile(mode='w', suffix='.py', delete=False) as f:
+            f.write("line1   \n")
+            f.write("line2\t\n")
+            f.write("line3\n")
+            temp_path = f.name
+
+        try:
+            fixer = AutoFixer()
+            result = fixer.remove_trailing_whitespace(temp_path)
+
+            assert result.success is True
+            with open(temp_path, 'r') as f:
+                content = f.read()
+            assert content == "line1\nline2\nline3\n"
+        finally:
+            os.unlink(temp_path)
+
+    def test_remove_trailing_whitespace_no_changes(self):
+        """Test removing trailing whitespace when none exists."""
+        with tempfile.NamedTemporaryFile(mode='w', suffix='.py', delete=False) as f:
+            f.write("line1\nline2\n")
+            temp_path = f.name
+
+        try:
+            fixer = AutoFixer()
+            result = fixer.remove_trailing_whitespace(temp_path)
+
+            assert result.success is True
+        finally:
+            os.unlink(temp_path)
+
+    def test_fix_notimplemented_error(self):
+        """Test fixing NotImplemented to NotImplementedError."""
+        with tempfile.NamedTemporaryFile(mode='w', suffix='.py', delete=False) as f:
+            f.write("def foo():\n    raise NotImplemented\n")
+            temp_path = f.name
+
+        try:
+            fixer = AutoFixer()
+            result = fixer.fix_notimplemented_error(temp_path)
+
+            assert result.success is True
+            with open(temp_path, 'r') as f:
+                content = f.read()
+            assert "raise NotImplementedError" in content
+        finally:
+            os.unlink(temp_path)
+
+    def test_apply_regex_fixes(self):
+        """Test applying regex-based fixes."""
+        with tempfile.NamedTemporaryFile(mode='w', suffix='.py', delete=False) as f:
+            f.write("old_value = 1\nold_value = 2\n")
+            temp_path = f.name
+
+        try:
+            fixer = AutoFixer()
+            result = fixer.apply_regex_fixes(
+                temp_path,
+                r"old_value",
+                "new_value"
+            )
+
+            assert result.success is True
+            with open(temp_path, 'r') as f:
+                content = f.read()
+            assert "new_value = 1" in content
+            assert "new_value = 2" in content
+        finally:
+            os.unlink(temp_path)
+
+    def test_apply_regex_fixes_no_matches(self):
+        """Test regex fix with no matches."""
+        with tempfile.NamedTemporaryFile(mode='w', suffix='.py', delete=False) as f:
+            f.write("other_value = 1\n")
+            temp_path = f.name
+
+        try:
+            fixer = AutoFixer()
+            result = fixer.apply_regex_fixes(
+                temp_path,
+                r"nonexistent",
+                "replacement"
+            )
+
+            assert result.success is True
+            assert result.fixes_applied == 0
+        finally:
+            os.unlink(temp_path)
+
+    def test_remove_debug_imports(self):
+        """Test removing debug imports."""
+        with tempfile.NamedTemporaryFile(mode='w', suffix='.py', delete=False) as f:
+            f.write("import ipdb\nimport pdb\ncode here\n")
+            temp_path = f.name
+
+        try:
+            fixer = AutoFixer()
+            result = fixer.remove_debug_imports(temp_path)
+
+            assert result.success is True
+            with open(temp_path, 'r') as f:
+                content = f.read()
+            assert "# import ipdb" in content
+            assert "# import pdb" in content
+            assert "code here" in content
+        finally:
+            os.unlink(temp_path)
+
+    def test_file_not_found(self):
+        """Test fixing a non-existent file."""
+        fixer = AutoFixer()
+        result = fixer.remove_trailing_whitespace("/nonexistent/file.txt")
+
+        assert result.success is False
+        assert "no such file" in result.error_message.lower() or "not found" in result.error_message.lower()